Monolithic concrete form



Sept. 2, 1941.

I W. H. JENKINS MONOLITHIC CONCRETE FORM Filed Nov. 25. 1938 2 Sheets-Sheet 2 4 36' 10 1 36 j 1- 62 v 58 57 M- 62 57 36 59 e0 INVENTOR. W. H. JENKINS.

\ ATTORN Patented Sept. 2, 1941 UNITED TES TENT ()FFICE 6 Claims.

This invention relates to improvements in monolithic conduit forms.

The general object of this invention is to provide an improved form for constructing conduits.

Another object of the invention is to provide an improved form for constructing the portion of monolithic conduit above the invert.

Other objects and the advantages of this invention will be apparent from'the following description taken in connection with the accompanying drawings, wherein:

Fig. 1 is an end view of a unit of my improved form shoun'ng it in position on the invert section of the conduit;

Fig. 2 is a side elevation of one unit of the form and a fragmentary side elevation of an adjoining unit;

Fig. 3 is a section taken on line 3-3 of Fig. 1;

Fig. 4 is a fragmentary top plan view of the unit shown in Fig. 1;

' Fig. 5 is an enlarged fragmentary section taken on line 5-5 of Fig. 3;

Fig. 6 is an enlarged fragmentary section taken on line 6-6 of Fig. 3;

Fig. 7 is a view similar to Fig. 1 showing a crown member on the forms; and

Fig. 8 is an enlarged fragmentary section taken on line 88 of Fig. 3.

Referring to the accompanying drawings by my improved form generally at H]. The form unit I is adapted to be positioned on the previously formed invert section II which, as shown, includes a base portion I2, spaced side return walls 13, and outer side steps Id. The unit I!) includes an inner form l which is formed of two opposed sections [6 and outer side forms [1.

Each of the sections l6 includes a base'plate l8 having a plurality of longitudinally spaced,

reference characters I have indicated a unit of upwardly extending rib-s I9 thereon which are 40 mortised as at 23 to receive a longitudinally'ex- 7 tending stringer 24 which extends downwardly over a portion of theplate I 8. At their upper ends each of the ribs 19 engages and is nailed to a longitudinally extending stringer 25. Posisheathing 26 which is shown as formed of a plurality of longitudinally extending boards 21 nailed to the ribs. Onthe outer face of the sheathing 26 I provide a facing 28 preferably of thin metal which is nailed to the sheathing.

As clearly'shown in Fig. 6 the stringer 24 is connected to the sheathing 26 by a plurality of carriage bolts and nuts 29, the head of the carriage bolts being countersunk in the sheathing. Each of the outer side forms I! includes a base plate 30 having a plurality of longitudinally spaced, upwardly extending ribs 3| thereon which are secured thereto as by nailing. 'The inner surface of each of the ribs 3! is shaped to extend upwardly and inwardly in a parabolic curve and the outer surface is somewhat similarly shaped. The inner upper ends of opposed ribs 3| when the unit is set up are spaced a predetermined distance apart and do not completely encompass the inner form l5.

The upper ends of the ribs 3| are connected by a longitudinally extending stringer 32 which is nailed to each of the ribs. Positioned on the inner faces of the ribs 3| I provide sheathing 33 which is shown as formed of a plurality of longitudinally extending boards 32 nailed to the ribs. On the outer face of the sheathing 33 I preferably provide a facing 35 of thin metal which is nailed to the sheathing. Alongside a plurality of the ribs 3| I provide a plurality of vertical timbers 36 which are nailed to adjacent ribs and the plate 30 and extend upwardly a predetermined distance above the ri=bs 3|. Adjacent their lower ends the ribs 3| are connected by a longitudinally extending stringer 31 which is nailed to the ribs 3| and the vertical members 36.

' In operation the two sections I6 of the inner form are secured together by bolts 38 and nuts 89 the bolts being positioned in previously formed apertures 40 in the stringers 25 (see Fig. 8). The inner form is positioned on the invert [2 with the metal facing 28 engaging the inner faces of the invert return walls [4. The form [5 is sup ported and leveled by means of a plurality of wedges 4| and block members 42.

Opposite vertical timbers 36 are connected by transverse timbers 43 which are secured to the vertical timbers as by bolts and nuts 44. To prevent longitudinal movement of the vertical timbers 36 1 provide planks 36' which rest on the transverse members 43 and are notched as at 36" to-receive the vertical timbers 43. The upper ends of the outer forms I! are retained in tioned on the outer faces of the ribs I9 I provide paced relation to the inner form I5 by a plurality of blocks 44 which are suspended from the transverse timbers 43 as by wires 45.

Adjacent the bottom on each side the inner form [5 and the outer form I! are clamped together by a plurality of bolts 46 and wing nuts 41. As clearly shown in Fig. 5 the heads of the bolts 46 engage the longitudinal inner stringer 24 and the shank passes through previously formed apertures 48 in'the stringer 24 similar apertures 49 in the inner sheathing 26 and facing 28 through similar apertures 50 in the outer sheathing 33 and facing 35 and through similar apertures 5| in the outer longitudinal stringer 3! withthe wing nut 41 engaging the stringer 31. Between the facings 28 and 35 a sleeve member 52 surrounds each of the bolts 45. To

prevent outward bulging of the outer forms when concrete is poured a longitudinal timber or support member 53 is positioned between the outer edge of the ribs 3| and the inner edge of the vertical timbers36; l

After the inner'andouter forms are correctly positioned'on" the invert l2 concrete is poured into the space between the inner and outer forms up to the upper ends of the outer forms, the block members 44 beinglremoved shortly before the level of'the' concrete reachesfthem.

' When forming small conduits the' crown ofthe conduit betweenthe-upper ends of the outer forms" is finished 'by hand; but when forming large conduits 'a' crown-form may-be provided such" as indicated at"55' in Fig. 7. As shown the" crown form55 includes spaced longitudinal side stringers 5fiwhich' are adapted to engagethe stringers 32 'and a plurality of longitudinally.

outer form including a pair of members each including a plurality'of longitudinally spaced ribs, a longitudinal stringer member connecting the upper ends of said ribs at each side, said stringer members being spaced apart leaving an opening in the upper portion of the outer form, a longitudinal stringer member at each side adjacent the lower ends of said ribs and connected to the ribs, sheathing on the inner face of said ribs, vertically extending frame members connected to the rib members, transverse members connecting said vertical frame members, longitudinally extending members engaging the inner faces of said vertical members and engaging the outer faces of said rib members, and 'a crown member disposed between said pair of members.

2. For use with an invert portion of a concrete conduit including spaced side return walls, an outer form including a pair of members each including a plurality of longitudinally spaced ribs, a longitudinal stringer member connecting the upper ends of said ribs at each'side, said stringer members being spaced apart leaving an opening in the-upperportion of the outer form, 'a longitudinal stringermember at each side adjacent the lowerends of said ribs and connected to the ribs, sheathing oitrtheiinner face of said'ribs.

, a crown'membe r, said crown m'emlber includcentral stringer 58 the Sheathing 'SS has a 'plu-J rality' of 'aprturestZttherein. The crown'form is held dorm? in engagement'with theside forms I! by"wedges"63 positionedbetween the central stringer T58" and the transverse: timbers 43. After thecrown form 55is'placed-in'position the crown concrete is forced into the spacebelow the crown formandthe topcf the inner form by cement gun nozzles inserted inthe aper-@ tures'62.

To-strip the unitlfl from a completed conduit the bolts 46 are removed and then if convenient outer form including a pair of membersieach including a plurality of longitudinally" spaced ribs, a longitudinal top stringer member connecting the upper ends of said ribs at each's'ide, said stringer members being spaced apart :leaving an opening in the upper portion'o'fthe outer form, a longitudinal stringer member at each side adjacent the lower ends of said'ribsand connected 7 to the ribs, sheathing on the inner face of said ribs, means passing through said stringer: members and 'overf'the adjacent return 'wall and adapted to secure the outer mold member in po-' sition, vertically extending frame. members connected to the rib members, transverse members connecting said vertical frame members and spacer blocks supported by said hanger members,

, stringer,.rib-s'connecting saidside and intermediparent that I haveiprovideda novel form'devi'ce for "forming monolithic concrete conduits which is'simple' in construction and highly'efii cient in w H i c 1 I Having thus described myinvention I claim:

' 1'. For use with an invertportion of a'concrete conduit including spac'ed" side-return walls, an

ate crownrstringers, a sheathing on the inner rality of. longitudinally spaced'ribs, a longitudinalstringer member connecting the upper-ends of said outer ribs at'each side, a longitudinal stringerlmember adjacent the lower ends of said outer ribs'andrconnected to the ribs ateach side, a covering 011 the inner face of said'cuter form ribs, spaced, upwardly directed, frame members disposed adjacent to said outer form rib members, transverse members connecting said frame members, hanger members suspended from said transverse frame members and spacer blocks supported by said hanger members, said spacer blocks being disposed Within the outer form member.

5. For use with an invert portion of a concrete conduit including spaced side return walls, an outer form including a pair of members each including a plurality of longitudinally spaced ribs, connecting members joining the upper ends of said ribs at each side, said connecting members being spaced apart leaving an opening in the upper portion of the outer form, a longitudinal stringer member at each side adjacent the lower ends of' said ribs and connected to the ribs, sheathing on the inner face of said ribs, upwardly directed frame members disposed adjacent to the in the upper portion of the outer form, a longi-' tudinal stringer member at each side adjacent the lower ends of said ribs and connected to the ribs, sheathing on the inner face of said ribs, a frame including upwardly directed members disposed adjacent to said ribs, and releasable means engaging the upwardly directed members and the ribs to support the latter.

WILLIAM H. JENKINS. 

